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ZHANG, GUOJUN. "CRYSTALLINE POLYMERS IN MULTILAYERED FILMS AND BLEND SYSTEMS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1404923073.
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Ogawa, Hiroki. "Phase Separation and Dewetting in Polymer Blend Thin Films." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/65600.
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Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第14104号
工博第2968号
新制||工||1440(附属図書館)
26392
UT51-2008-L159
京都大学大学院工学研究科高分子化学専攻
(主査)教授 金谷 利治, 教授 伊藤 紳三郎, 教授 瀧川 敏算
学位規則第4条第1項該当
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Hunter, Simon. "Solution-processable organic blend semiconductors for next generation thin-film transistor applications." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/40418.
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Organic semiconductors display a wide array of enticing properties for the fabrication of novel electronic devices. Mechanical flexibility provides the potential for robust, conformable devices; while wide-area and low-temperature deposition enables the manufacture of low-cost, disposable electronics. This means that the commercial applications should be wide-ranging, as long as the performance and stability of devices based on organic semiconductors are sufficient. One of the most promising organic thin-film transistor (OTFT) systems that have been demonstrated in recent years involves the blending of small molecule and polymer organic semiconductors. A blend of the high hole mobility small molecule 2,8-difluoro 5,11 triethylsilylethynyl anthradithiophene (diF-TES ADT) with the amorphous semiconducting polymer poly(triarylamine) (PTAA) is investigated in this thesis. This blend system has been shown to allow considerable control over processing from solution and charge carrier mobilities of up to 3 cm^2/Vs. The aim of this thesis is to provide a deeper understanding of the critical charge transport and stability characteristics of this blend system, while also investigating the system's suitability to a high-throughput spray-deposition technique. In the first part of this thesis the fundamental charge transport characteristics of the diF-TES ADT:PTAA blend system are investigated. The densities of band-gap tail states in blend films of differing composition are found to be exhibit considerable thermal broadening at low temperatures, and at high temperatures are controlled by the concentration of the small molecule component in the blend. In the second part of the work the electrical and environmental stability of blend OTFTs is studied. The devices exhibit state-of-the-art bias stability in an inert environment, however exposure to air and elevated temperatures highlights some interesting degradation pathways which are investigated. Finally, the blend system was used with a high-throughput spray deposition technique. Subsequent spray deposition of semiconductor and ultra-thin dielectric layers was demonstrated, resulting in the fabrication of low-power OTFTs operating at -4 V and exhibiting hole mobilities on the order of 1 cm^2/Vs.
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Ng, Annie, and 吳玥. "Polymer blend film for photovoltaic applications optical characterization and solar cell performance." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196013.
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Sunlight is sustainable, clean and readily available energy source, which is one of the potential alternatives to the traditional energy sources. Recently, the organic photovoltaics (OPVs), in particular polymer solar cells (PSCs), have attracted increasing attention owing to their outstanding properties such as low cost, lightweight, flexible, allowing vacuum-free fabrication process and thin-film architecture. These advantageous material and manufacturing features of PSCs provide the opportunities for many novel applications. However, the lower power conversion efficiencies (PCEs) of PSCs compared to inorganic solar cells hinder their competition in the marketplace.
This thesis covers the basic principles of the PSC, strategies for enhancing PCEs as well as the recent development of PSCs. The importance of the source materials has been also demonstrated and discussed. Due to a large number of possibilities, limited resources and time, it is not feasible to do all the work experimentally. Therefore, for continuing advance development of PSCs, the device performance should be modeled as a function of material parameters, which requires the knowledge of material properties, in particular the complex index of refraction N= n - ik. Accurate determination of the optical functions of the active layers and light trapping layers commonly used in PSCs by using the spectroscopic ellipsometry (SE) has been demonstrated. In order to acquire reliable solutions, the methodology including multiple sample analysis, combinations of different measurement techniques, selection of models, the rigorous fitting procedures and the independent verification have been proposed. The obtained information can be used in the simulation to optimize device architectures, model device performance as well as characterize novel materials.published_or_final_version
Physics
Doctoral
Doctor of Philosophy
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Park, Dongsik. "Self-Assembled Patterns of Block Copolymer/Homopolymer Blends." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1209071160.
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Balcells, Eduardo. "I. Solubility and blend studies of nitrocellulose II. Relaxation properties of thin film coatings: the role of surface topography." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/80171.
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In the first part of this two part thesis, interaction parameters of nitrocellulose with various solvent systems were investigated by Inverse Gas Chromatography. From these data, the solubility parameters of nitrocellulose were determined at a series of nitration levels which were used to guide the selection of suitable plasticizers for nitrocellulose films. Subsequent dynamic mechanical experiments were then used to evaluate the effectiveness of the blend formulations in broadening the glass transition dispersion of the nitrocellulose blended films; in addition, stress-strain experiments were done in order to evaluate the tensile modulus of the nitrocellulose blends.
In the second part of this thesis, both dynamic mechanical thermal analysis and dielectric thermal analysis were used to evaluate the relaxation properties of thin film polysulfone coatings and the effect of substrate surface topography on these properties. Both dynamic mechanical and dielectric thermal analysis revealed that the topographical nature of the substrate influenced the linear viscoelastic properties of the thin film coatings and that the extent of this influence was dependent on the coating thickness.Master of Science
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Campbell, Sam Nicole. "Blend it Like Beckett: Samuel Beckett and Experimental Contemporary Creative Writing." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/etd/3769.
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Samuel Beckett penned novels, short stories, poetry, stage plays, radio plays, and scripts—and he did each in a way that blended genre, challenged the norms of creative writing, and surprised audiences around the globe. His experimental approach to creative writing included the use of absurdism, genre-hybridization, and ergodicism, which led to Beckett fundamentally changing the approach to creative writing. His aesthetics have trickled down through the years and can be seen in contemporary works, including Aimee Bender’s short story collection The Girl in the Flammable Skirt and Mark Z. Danielewski’s novel House of Leaves[1]. By examining these works in comparison to Beckett, this project hopes to illuminate the effects of Beckett’s experimentation in form and genre on contemporary creative writing.
[1] The word ‘house’ appears in blue to honor Danielewski’s decision to have the word printed in that color each time it appears in his novel.
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HAGHIGHI, HOSSEIN. "Sviluppo di film attivi a base di chitosano per packaging alimentare sostenibile." Doctoral thesis, Università degli studi di Modena e Reggio Emilia, 2020. http://hdl.handle.net/11380/1201046.
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L'attuale tendenza nel confezionamento degli alimenti è orientata alla sostituzione di polimeri non biodegradabili a base di petrolio con materiali di imballaggio ecologici e che possano prolungare anche la shelf-life degli alimenti. In questo contesto, il progetto Ph.D. ha preso in considerazione lo sviluppo di film misti a base di chitosano arricchiti con composti antimicrobici naturali (oli essenziali) e di sintesi (etil lauroil arginato) per applicazioni di confezionamento alimentare sostenibile. L'intero progetto è stato diviso in cinque parti principali.
Il capitolo I presenta una breve introduzione sui recenti progressi dei film costituiti da miscele a base di chitosano. Il motivo per cui è stato scelto il chitosano come biopolimero principale in questo studio e nella revisione della letteratura riguardante la miscelazione del chitosano con altri biopolimeri è stata descritta.
Nel capitolo II, i film attivi a base biologica e doppio strato sono sviluppati mediante tecnica solvent casting, usando chitosano e gelatina come biopolimeri, glicerolo come plastificante e etil lauroil arginato (LAE) come composto antimicrobico. I risultati hanno mostrato che i film di miscelazione presentavano una resistenza alla trazione e un modulo elastici più elevati e una permeabilità al vapore acqueo inferiore rispetto ai film a doppio strato (p <0,05). I film bilayer hanno dimostrato un’efficace barriera contro la luce UV e valori di trasparenza inferiori (p <0,05). Gli spettri FT-IR hanno indicato la presenza di interazioni tra chitosano e gelatina, in particolare interazioni elettrostatiche e formazione di legami idrogeno. Tuttavia, l'aggiunta di LAE non ha interferito nella struttura della rete. I film attivi contenenti LAE (0,1%, v / v) hanno inibito la crescita di quattro patogeni alimentari tra cui Listeria monocytogenes, Escherichia coli, Salmonella typhimurium e Campylobacter jejuni.
Nel capitolo III, sono sviluppati film a base di miscela chitosano-gelatina arricchita con cannella, citronella, chiodi di garofano rosa, noce moscata e oli essenziali di timo (1%, v / v) e le loro proprietà fisiche, ottiche, meccaniche, di barriera all'acqua e microstrutturali sono state valutate per applicazioni di confezionamento alimentare attivo. I risultati hanno confermato le interazioni intermolecolari tra i gruppi funzionali degli oli essenziali con i gruppi idrossile e amminico della rete di film di chitosano-gelatina. L'incorporazione di diversi oli essenziali ha migliorato notevolmente le proprietà di barriera UV. I film sviluppati, con particolare riguardo a quelli integrati con l'olio essenziale di timo, erano efficaci contro i quattro comuni patogeni alimentari testati.
Il capitolo IV si concentra sullo sviluppo di film attivi basati sulla miscelazione di biopolimeri naturali (chitosano) e sintetici (polivinilico alcool). Sono stati sviluppati film in miscela di chitosano, polivinil alcool e LAE, incorporato in questi film a diverse concentrazioni (1-10%, p / p). I risultati hanno mostrato che alti livelli di LAE hanno influenzato negativamente sulle proprietà di barriera meccanica e permeabilità all'acqua. Anche in questo caso film attivi sviluppati erano efficaci contro quattro agenti patogeni alimentari testati.
Il capitolo V rappresenta la conclusione di questa tesi, e presenta una sintesi dei punti salienti dei risultati importanti, ottenuti in questo studio.The current trend in food packaging is oriented towards the substitution of non-biodegradable petroleum-based polymers by packaging materials that are eco-friendly and can prolong the food shelf life as well. In this context, this Ph.D. project aims to the development of chitosan-based blend films enriched with natural (essential oils) and synthetic (ethyl lauroyl arginate) antimicrobial compounds for sustainable food packaging applications. The overall project has been divided into five main parts. The brief description of each chapter is presented here: Chapter I presents a brief introduction to the recent advances of chitosan-based blend films for food packaging applications. The reason for selecting chitosan as the main biopolymer in this study and literature review concerning blending chitosan with other biopolymers has been described. Chapter II aims to develop blend and bilayer bio-based active films by solvent casting technique, using chitosan and gelatin as biopolymers, glycerol as a plasticizer and ethyl lauroyl arginate (LAE) as an antimicrobial compound. The results showed that blend films had higher tensile strength and elastic modulus and lower water vapor permeability than bilayer films (p<0.05). Bilayer films demonstrated as effective barriers against UV light and showed lower transparency values (p<0.05). FT-IR spectra indicated that interactions existed between chitosan and gelatin due to electrostatic interactions and hydrogen bond formation. However, the addition of LAE did not interfere in the network structure. Active films containing LAE (0.1%, v/v) inhibited the growth of four food bacterial pathogens including Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, and Campylobacter jejuni. Chapter III focuses to develop films based on chitosan-gelatin blend enriched with cinnamon, citronella, pink clove, nutmeg, and thyme essential oils (1%, v/v) and evaluating their physical, optical, mechanical, water barrier and microstructural properties for active food packaging applications. The results confirmed intermolecular interactions between functional groups of the essential oils with the hydroxyl and amino groups of the chitosan-gelatin film network. The incorporation of different essential oils notably improved the UV barrier properties. The developed films, with special regards for those including thyme essential oil, were effective against four common food bacterial pathogens. Chapter IV aims to develop active films based on blending chitosan and polyvinyl alcohol enriched with LAE at different concentrations (1-10%, w/w). The results showed that high LAE levels negatively affected mechanical and water barrier properties. Addition of LAE improved UV barrier properties. The developed active films were effective against four common food bacterial pathogens.
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RAJABINEJAD, HOSSEIN. "Keratin Based Material For Perspective Bio-Application." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2697565.
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Keratin has natural characteristic for applying in biomaterial field as a biocompatible matrix like tissue regeneration, proliferation, and cell adhesion or drug career in the shape of microcapsules or microsphere. Because of the amino acid inherent structure, keratin extraction needs to be well designed to meet the particular requirement for applying in desired applications such as integrate with different molecules, drug releases, wound healing or biocompatible film. Keratinous sources such as wool, feathers are valuable by-products that abundantly present in nature. Although wool has valuable material in especially in textile industry, massive amount of low-grade wool cannot be utilized in textile and inevitably end up as a waste stream. Because of high cystine content of keratin, solubilization and extraction of keratin is a problematic process compared with other natural polymers such as collagen and chitosan. Using keratin in different level especially in large-scale requires understanding final properties of keratin which is strongly depends on producing procedure.. The interest towards drug career and microcapsules based on non-toxic, biodegradable and biocompatible polymers, such as proteins, is increasing considerably.
In this work, keratin from wool fibers was extracted with oxidation, reduction, sulfitolysis, and superheated water hydrolysis methods. The effect of each method on obtained keratin properties are discussed and particularly reported how each extracted keratin influenced by the extraction process. In particular, all different samples of extracted keratin were characterized by molecular weight determination, FT-IR and NIR spectroscopy, amino acid analysis, and thermal behavior and the archived data were compared with reporting of previous studies with the emphasis of advantage and limitation of each extraction method.
In the other part of the study, special attention are given to produce microcapsule and film from keratin-based material in line with biomaterial application. Microcapsules were prepared using water-soluble keratin, known as keratoses, with the aim of encapsulating hydrophilic molecules. The obtained keratin via oxidizing extraction of pristine wool, were utilized as shell part of the microcapsules which produced by sonication method. Production of the microcapsules was carried out by a sonication method.
The microencapsulation and dye encapsulation yields were obtained by UV-spectroscopy. In addition, morphological structure of microcapsules was studied by light microscopy, SEM, and AFM and thermal properties of microcapsules were investigated by DSC.
The molecular weights of proteins analyzed with gel-electrophoresis indicates the extracted keratoses has suitable molecular weight range for bio-application, and also the results confirmed that the hydrophilic dye (Telon Blue) was introduced inside the keratoses shells. The final microcapsules diameter ranged from 0.5 to 4 µm.
One part of the experimental work is dedicated to producing keratin blend film with polyvinyl alcohol (PVA). PVA has been chosen because of its biocompatible and biodegradable properties which make this polymer as a promising candidate in the bio-field area. Blend of Polyvinyl alcohol (PVA) and keratoses were prepared with the aim of producing bio-compatible material proper for film and fiber structure mainly to improve the mechanical properties of obtained keratoses. Aqueous solution of keratoses and PVA was prepared for solution casting method. Blended films were characterized by, SEM, FT-IR spectroscopy and Differential scanning colorimetry and tensile properties.
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Abrahams, Dhielnawaaz. "Charge Transfer and Capacitive Properties of Polyaniline/ Polyamide Thin Films." University of the Western Cape, 2018. http://hdl.handle.net/11394/6361.
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Magister Scientiae - MSc (Chemistry)Blending polymers together offers researchers the ability to create novel materials that have a combination of desired properties of the individual polymers for a variety of functions as well as improving specific properties. The behaviour of the resulting blended polymer or blend is determined by the interactions between the two polymers. The resultant synergy from blending an intrinsically conducting polymer like polyaniline (PANI), is that it possesses the electrical, electronic, magnetic and optical properties of a metal while retaining the poor mechanical properties, solubility and processibility commonly associated with a conventional polymer. Aromatic polyamic acid has outstanding thermal, mechanical, electrical, and solvent resistance properties that can overcome the poor mechanical properties and instability of the conventional conducting polymers, such as polyaniline.
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Gilbert, Ebony P. "Blind Allegiance." Digital Commons at Loyola Marymount University and Loyola Law School, 2015. https://digitalcommons.lmu.edu/etd/159.
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Qiu, Shuzhen. "Preparation and characterization of Matrimid/P84 blend films." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18803.
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Master of ScienceDepartment of Chemical Engineering
Mary Rezac
Polymeric membranes have been playing important roles in gas or liquid separations. Polyimide polymers are of interest due to their commercially availability along with good transport, thermal and mechanical properties. In this study, two common commercial polyimide polymers, Matrimid and P84 were blended, to combine the good transport property of Matrimid with the plasticization resistance of P84. Matrimid/P84 blend solutions ranging from 0-100 wt. % Matrimid were prepared to make blend films. Physical properties (density, d-spacing, thickness), transport properties (permeability of H2, N2, CH4, Ar, He, CO2, and gas pairs selectivity), thermal property (mass loss curves of TGA), and liquid solutes (water, methanol, toluene, butanol, 1-propanol, 2-propanol) desorption behavior were measured or characterized. Rules of changing behavior of the properties with mass fraction of Matrimid were investigated, summarized, and interpreted mathematically. As Matrimid mass fraction increases, there are more mobility and space between polymer chains, therefore there are smaller density, larger d-spacing, larger fractional free volume (FFV) and larger permeability. The selectivity-permeability relationship follows the trade-off line. Thermal mass loss curve of the blend films in air have presented intermediate characteristic with rising fraction of Matrimid compared to individual polymers. A partial-miscible behavior has been found from the correlation between permeability and FFV. The desorption behavior was found to be reasonably described by the case III model, where the diffusion rate is similar with relaxation rate of polymers.
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Zhang, Zhipeng, Wenckstern Holger von, Jörg Lenzner, Michael Lorenz, and Marius Grundmann. "Visible-blind and solar-blind ultraviolet photodiodes based on (InxGa1-x)2O3." American Institute of Physics, 2016. https://ul.qucosa.de/id/qucosa%3A23547.
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UV and deep-UV selective photodiodes from visible-blind to solar-blind were realized based on a
Si-doped (InxGa1–x)2O3 thin film with a monotonic lateral variation of 0.0035
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Steiger, Isadora. "Skinny Girls Bleed Flowers, and Other Sick Lies." Scholarship @ Claremont, 2018. http://scholarship.claremont.edu/scripps_theses/1133.
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This short film visualizes the experiences of seven Scripps students who have or have had eating disorders, using interview audio and projected imagery to critique existing media portrayals of eating disorders, as well as humanizing those who actually suffer from them.
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Geoghegan, Mark. "Surface induced phase transitions in thin polymer blend films." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319888.
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Chen, Yuxuan. "Morphology Development of Block Copolymer and Homopolymer Blend Films." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430870587.
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Zhang, Yue Zhang. "Phase Separation of Polymer-grafted Nanoparticle blend Thin Films." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1494885057468539.
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Coveney, Sam. "Fundamentals of phase separation in polymer blend thin films." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/8146/.
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In this Ph.D. thesis, I investigate fundamental aspects of phase separation in polymer-blend thin films by unifying 1D phase equilibria with film evolution phenomena. I begin by extending a Hamiltonian phase portrait method, useful for visualising and calculating phase equilibria of polymer-blend films, allowing the method to be applied to systems with no convenient symmetries. Consideration of equilibria suggests a thermodynamic mechanism of film roughening, whereby laterally coexisting phases could have different depths in order to minimise free energy. I then make use of the phase portraits to demonstrate that simulations of lateral phase separation via a transient wetting layer, which conform very well with experiments, can be satisfactorily explained by 1D phase equilibria and a surface bifurcation mechanism involving effective boundary conditions caused by the film surfaces. Lastly, to tie together the aforementioned work, I introduce a novel 3D model of coupled phase separation and dewetting, for which I solved the problem of including a general non-uniform composition profile in the depth direction between the film surfaces. Pattern formation, in which surface roughening shadows the phase separation, seems to be determined by an interplay between dewetting kinetics and underlying phase equilibria.
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Mokarian-Tabari, Parvaneh. "Controlling the morphology of spin coated polymer blend films." Thesis, University of Sheffield, 2010. http://etheses.whiterose.ac.uk/15113/.
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Thin films of polymer mixtures made by spin-coating can phase separate in two ways - by forming lateral domains, or by separating into two distinct layers. The latter situation - self-stratification or vertical phase separation - could be advantageous in a number of practical applications, such as polymer photovoltaics. In our experiments, we have used time-resolved small-angle light scattering and light reflectivity during spin coating to study the structure development in PS/PMMA and PFB/F8BT blends, solution cast in toluene. A sample cell was designed, made and mounted on the apparatus to manipulate the evaporation rate. Having solved the Meyerhofer equation for thinning rate and by fitting the model to the experimental data, we are able to extract the evaporation rate of toluene during spin coating. We demonstrate that, by controlling the evaporation rate during the spin-coating process, we can obtain either selfstratification or lateral phase separation in the same system. We relate this to a previously hypothesised mechanism for phase separation during spin coating in thin films, according to which a transient wetting layer breaks up due to a Marangoni-type instability driven by a concentration gradient of solvent within the drying film. Our results show that a high evaporation rate leads to a laterally phase separated structure, while reducing the evaporation rate suppresses the interfacial instability and leads to a self-stratified final film. Using the set up we developed to control the morphology through evaporation rate, we made preliminary photovoltaic devices. It is possible to control the efficiency of the polymer photovoltaics by means of process parameters such as evaporation rate.
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Pearson, Andrew. "Correlating structure with optoelectronic functionality in polymer:fullerene blend films." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/2332/.
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In this thesis the influence of processing conditions on the structure and optoelectronic properties of conjugated polymer:methanofullerene blend thin-films has been investigated. These conditions strongly impact upon the efficiency with which blend films may produce a photocurrent when fabricated into an Organic Photovoltaic (OPV) device. Using the model system P3HT:PCBM, it is shown that films undergo a three-stage drying process upon casting. Heterogeneous growth of P3HT crystallites occurs once the solid fraction in the film exceeds 50 wt%. Measurements from spectroscopic ellipsometry (SE) and grazing-incidence wide-angle X-ray scattering (GIWAXS) suggest a correspondence between enhanced polymer crystallinity and the strength of the π-π* electronic transition in the polymer absorption spectrum. In-situ measurements of a blend during thermal annealing evidence the evolution of residual solvent loss upon heating, volume relaxation, phase separation and increased electronic conjugation of P3HT upon cooling. The glass transition of P3HT:PCBM blend films, measured in a thin-film geometry, is found to correlate with the minimum effective annealing temperature for improving the power conversion efficiency of thermally annealed OPVs. As-cast films with 20 to 60 wt% PCBM exhibit two glass transitions, an observation that may indicate the existence of two compositionally distinct amorphous phases. Studies on a different polymer:fullerene blend system (PCDTBT:PC71BM), indicate a greater miscibility between materials compared to blends of P3HT:PCBM. In this system, thermal annealing is found to result in increased disorder in the polymer phase of the film, and also to drive excessive phase separation of PC71BM. It is argued that thermal annealing is unlikely to be an appropriate treatment for optimising the efficiency of OPVs based on PCDTBT:PC71BM blends. Finally, Helium Ion Microscopy (HeIM) is used to image the chemical composition of OPV applicable blend films with nanometer resolution, providing a powerful technique to correlate film morphology with device functionality in a range of organic opto-electronic devices.
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Ferrer, Danielle. "Casting." Scholarship @ Claremont, 2018. http://scholarship.claremont.edu/scripps_theses/1082.
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Kalloudis, Michail. "Thin polymer films of block copolymers and blend/nanoparticle composites." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7894.
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In this thesis, atomic force microscopy (AFM), transmission electron microscopy (TEM) and optical microscopy techniques were used to investigate systematically the self-assembled nanostructure behaviour of two different types of spin-cast polymer thin films: poly(isoprene-b-ethylene oxide), PI-b-PEO diblock copolymers and [poly(9,9-dioctylfluorene-co-benzothiadiazole)]:poly[9,9- dioctyfluorene-co-N-(4-butylphenyl)-diphenylamine], F8BT:TFB conjugated polymer blends. In the particular case of the polymer blend thin films, the morphology of their composites with cadmium selenide (CdSe) quantum dot (QD) nanoparticles was also investigated. For the diblock copolymer thin films, the behaviour of the nanostructures formed and the wetting behaviour on mica, varying the volume fraction of the PEO block (fPEO) and the average film thickness was explored. For the polymer blend films, the effect of the F8BT/TFB blend ratio (per weight), spin-coating parameters and solution concentration on the phase-separated nanodomains was investigated. The influence of the quantum dots on the phase separation when these were embedded in the F8BT:TFB thin films was also examined. It was found that in the case of PI-b-PEO copolymer thin films, robust nanostructures, which remained unchanged after heating/annealing and/or ageing, were obtained immediately after spin coating on hydrophilic mica substrates from aqueous solutions. The competition and coupling of the PEO crystallisation and the phase separation between the PEO and PI blocks determined the ultimate morphology of the thin films. Due to the great biocompatible properties of the PEO block (protein resistance), robust PEO-based nanostructures find important applications in the development of micro/nano patterns for biological and biomedical applications. It was also found that sub-micrometre length-scale phase-separated domains were formed in F8BT:TFB spin cast thin films. The nanophase-separated domains of F8BT-rich and TFB-rich areas were close to one order of magnitude smaller (in the lateral direction) than those reported in the literature. When the quantum dot nanoparticles were added to the blend thin films, it was found that the QDs prefer to lie in the F8BT areas alone. Furthermore, adding quantum dots to the system, purer F8BT and TFB nano-phase separated domains were obtained. Conjugated polymer blend thin films are excellent candidates for alternatives to the inorganic semiconductor materials for use in applications such as light emitting diodes and photovoltaic cells, mainly due to the ease of processing, low-cost fabrication and mechanical flexibility. The rather limited optoelectronic efficiency of the organic thin films can be significantly improved by adding inorganic semiconducting nanoparticles.
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Ford, T. A. "Long-lived excitations in conjugated polymer blend films and devices." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599107.
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This thesis discusses the formation and decay of long-lived excited states within thin films and light-emitting diodes based on blends of polyfluorene-derived conjugated polymers. A polymer blend comprises two different conjugated polymers mixed together in a complex morphology. The formation of triplet excitons is studied in the blend system comprising poly(9,90dioctylfluorene-co-benzothiadiazole) (F8BT) and poly(9,9-dioctylfluorene-co-bis-N,N-(4-butylphenyl)-bis-N,N-phenyl-1,4-phenylenediamene) (PFB). The formation efficiency of triplet excitons is found to be several times higher in the blend than in either of the pristine polymers. Triplet excitons are formed at the interfaces between the two different polymers and the formation rate may be reduced with an external electric field. Two distinct interfacial states are known to exist in the F8BT:PFB polymer blend, a short-lived polaron pair and a long-lived exciplex state. Efficient intersystem crossing is shown to occur in both states. The rate of intersystem crossing is calculated as (4.6 ± 1.6) x 106s-1 in the exciplex state and at least (2.2 ± 0.6) x 107s-1 in the polaron pair. Once formed, triplet excitons decay with two characteristic lifetimes, corresponding to free and trapped triplets. In a polymer LED, polaron pair states are formed from the association of injected electrons and holes. The fast rate of intersystem crossing noted in the polaron pair suggests that the single formation fraction in a polymer LED may differ from the 25% suggested by simple spin statistics. Two experimental methods are used to calculate the singlet fraction in an F8BT:PFB LED. The singlet fraction, at low applied voltage, is found to be below 20% which corresponds to a fast relaxation from the triplet polaron pair states to the triplet exciton.
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Phillips, Matthew David. "Magnetic field effects in conjugated polymer blend films and devices." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609464.
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Anselmo, Ana Sofia. "The morphology of polyfluorene : fullerene blend films for photovoltaic applications." Licentiate thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-7950.
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Polymer photovoltaic systems whose photoactive layer is a blend of a semiconducting polymer with a fullerene derivative in a bulk heterojunction configuration are amongst the most successful organic photovoltaic devices nowadays. The three-dimensional organization in these layers (the morphology) plays a crucial role in the performance of the devices. Detailed characterization of this organization at the nanoscale would provide valuable information for improving future material and architectural design and for device optimization. In this thesis, the results of morphology studies of blends of several polyfluorene copolymers (APFOs) blended with a fullerene derivative are presented. Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy was combined with dynamic Secondary Ion Mass Spectrometry (dSIMS) for surface and in-depth characterization of the blend films. NEXAFS was performed using two different electron detection methods, partial (PEY) and total (TEY) electron yield, which provide information from different depth regimes. Quantitative compositional information was obtained by fitting the spectra of the blend films with a linear combination of the spectra of films of the pure components. In blends of APFO3 with PCBM in two different blend ratios (1:1 and 1:4 of polymer:fullerene) NEXAFS data show the existence of compositional gradients in the vertical direction for both blend ratios, with clear polymer enrichment of the free surface. A series of APFOs with systematic changes in the side-chains was studied and it was shown that those small modifications can affect polymer:fullerene interaction and induce vertical phase separation. Polymer-enrichment of the free surface was clearly identified, in accordance with surface energy minimization mechanisms, and a compositional gradient was revealed already in the first few nanometers of the surface of the blend films. dSIMS showed that this vertical phase separation propagates throughout the film. It was possible to determine that as the polar character of the polymer increases, and thus the polymer:fullerene miscibility is improved, the tendency for vertical phase separation becomes stronger.Paper II was not published at the time of the licentiate defence and had the title: NEXAFS spectroscopy study of the surface composition in APFO3:PCBM blend films
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Dyer-Smith, Clare. "Spectroscopic studies of excited states in polyfluorene:small molecule blend films." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7128.
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In organic solar cells, understanding of interfacial processes and energy losses governing device performance is crucial to the development of new organic photovoltaic materials. This thesis reports on spectroscopic studies addressing the conditions for interfacial excited-state losses in donor-acceptor organic blends based on polyfluorene copolymers. The first chapter of results addresses the process of energy transfer in polyfluorene:fullerene blends. Novel fullerene materials based upon multiply substituted C60 and C70 are used in order to modify the energy levels, packing and photophysics in the blend. In these blends, a limitation becomes apparent in that an increase in the offset between the donor ionisation potential and the acceptor electron affinity (expected to increase the open circuit voltage) is accompanied by a loss in photocurrent and the formation of fullerene singlet and triplet states, above a threshold offset of 1.6 electronvolts. Spectroscopic measurements support a mechanism of resonant energy transfer from polymer to fullerene as a process leading to significant energy loss. In these polymers, the efficiency of hole transfer relative to fullerene intersystem crossing influences charge generation yield. The second chapter of results addresses charge transfer ('exciplex') emission as an important source of information about the photophysics of organic-organic interfaces. Blends of emissive polyfluorenes with n-type silole derivatives exhibit charge transfer emission from an interfacial state. The decrease in oscillator strength of the exciplex emission with exciplex energy is assigned to an increase in charge transfer character, explained either by the presence of electron withdrawing moieties, or an increase in solid-state ordering. The third results chapter presents a photophysical study of a silicon-bridged polyindenofluorene polymer blended with the fullerene PCBM. In this system the lifetime of the polymer triplet displays a dependence upon PCBM content in the film, indicating that the polymer triplet dynamics are influenced by interfacial processes.
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Yuan, Chuqing. "Topographic Pattern Directed Phase Separation in PAN/PMMA Blend Thin Films." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525754114090085.
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Giuriola, Alessandra <1988>. "blind blind blind Il tema della cecità nella letteratura, nel cinema e nel teatro della seconda metà del Novecento." Master's Degree Thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/2915.
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In questa tesi si analizza il tema della cecità nelle opere letterarie, cinematografiche e teatrali del periodo storico che va dal Secondo Dopoguerra a oggi. Il tema viene indagato e declinato in base ad uno schema generale di sotto-temi (ad esempio il tema del rapporto tra non visione e veggenza, o quello tra Io e Destino). Ogni singola opera citata, dunque, sarà analizzata e comparata ad altre, secondo l'ordine delineato da questa "griglia tematica".
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Walha, Fatma. "Elaboration de mélanges à base de Bio-polymères : Etude des corrélations entre structure, propriétés et transformation." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI075.
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Cette étude est une contribution à la mise au point d’un nouveau matériau filmogène multiphasique, originaire de ressources naturelles et destiné à l’emballage alimentaire. La voie proposée consiste à élaborer un mélange poly (acide lactique) [PLA]/ polyamide 11 [PA11] à différentes compositions; le principal avantage étant d’offrir un éventail de propriétés difficile à réunir sur un même polymère. Les différentes formulations, PLA/PA11, élaborées à l’état fondu dans une extrudeuse bivis ont été étudiés du point de vue des propriétés rhéologiques, thermique, mécanique et de la morphologie. Différents tiers-corps copolymères de structures diverses ont été utilisés, à différents taux, dans le but de promouvoir l’adhésion à l’interface des composants et améliorer les performances des mélanges ainsi conçus. La finalité est d’appréhender une formulation qui soit filmogène, tout en ayant un comportement en élongation, à l’état fondu, parfaitement compatible avec les conditions de transformation par extrusion gonflage de gaineThis study is a contribution to the development of a new biomaterial with suitable melt strength, stiffness-to-toughness balance, and the required thermal performance for food packaging applications. The proposed approach consists in preparing a mixture of poly (lactic acid) [PLA] / polyamide 11 [PA11] with different compositions; the main advantage being to offer a range of properties that are difficult to combine on the same polymer. The different formulations, PLA/PA11, processed in the molten state in a twin-screw extruder were studied from the side of rheological, thermal, mechanical and morphology. Different copolymers of various structures were used, at different rates, in order to promote the adhesion in the interface of the components and to improve the blend systems performances. The aim is to obtain a formulation that having an elongation behavior, in the molten state, perfectly compatible with the blowing process
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Cook, Steffan. "Photo-induced charge generation and recombination in conjugated polymer methanofullerene blend films." Thesis, Imperial College London, 2006. https://spectradspace.lib.imperial.ac.uk:8443/dspace/handle/10042/9.
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Polymer-fullerene blend films are of increasing interest in the field of organic solar cells. This thesis describes the use of transient absorption spectroscopy (TAS) as a means to study charge generation and recombination in these blend films. In blend films of P3HT and PCBM, the absorption spectrum associated with the positive and negative charges have been identified and the transient decay kinetics analysed to reveal the mechanisms leading to charge recombination losses in the films. The effects of annealing treatment, along with the effects of decreasing polymer regioregularity or different polymer chain terminating end-groups on the blend film properties and morphology are also discussed. For films with a low concentration of PCBM in polystyrene, absorption and emission from the individual PCBM molecules are observed. As the PCBM concentration is increased, aggregation related changes causes the absorption in the visible region to increase disproportionately, an additional emission peak at higher energies to appear and a decrease in the lifetime of the PCBM triplet excited state. These changes are linked to electronic interactions between fullerenes in a molecular crystal form of PCBM. Blends of F8BT polymer with PCBM show poor photovoltaic device performance. This is explained by the quick deactivation of the F8BT excited state by Förster energy transfer to the PCBM. As the PCBM excited state is stable compared to the charge separated state, the PCBM triplet is formed via inter-system crossing from the singlet to be the final product of photoexcitation. The high energy of the charge separated state is interpreted as a result of the high F8BT HOMO energy.
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Benson, Jessica J. "Spectroscopic studies of organic donor-acceptor blend films for solar cell applications." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/11386.
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Using several organic electron donor and electron acceptor materials, solution cast blend films were studied to better understand charge separation and excited state formation in thin films for organic solar cell applications.
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Feng, Jingxing. "Transport Phenomena in Polymeric Blends and Multilayer Films." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1548202751756984.
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Nguyen, Vu Anh. "Blends of Polydioctylfluorene (PFO) with polymeric and monomeric energy acceptors: correlation of fluorescence energy transfer and film morphology in breath figures and films." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24609.
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Thesis (Ph.D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008.Committee Chair: Tolbert, Laren; Committee Member: Collard, David; Committee Member: Lyon, Andrew; Committee Member: Srinivasarao, Mohan; Committee Member: Wilkinson, Angus
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Walheim, Stefan. "Micrometer and sub-micrometer structure formation of phase separating polymer films." [S.l. : s.n.], 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8885132.
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Nallapaneni, Asritha. "BIOMIMETIC NON-IRIDESCENT STRUCTURAL COLORATION VIA PHASE-SEPARATION OF COMPATIBILIZED POLYMER BLEND FILMS." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1590749223865508.
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Björström, Cecilia. "Morphology studies of thin films of polyfluorene: fullerene blends." Licentiate thesis, Karlstad University, Division for Engineering Sciences, Physics and Mathematics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-2361.
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The formation of thin films of polymer blends by spin-coating from solution is characterised by rapid solvent quenching, a process that results in non-equilibrium morphologies. Thin films of conjugated polymer blends are used as the active material in polymer solar cells, in which the morphology may have drastic effects on device performance.
In this thesis results from morphology studies are presented for spin-coated thin films of polyfluorenes and co-polymers of polyfluorene blended with the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The surface morphology was investigated by atomic force microscopy (AFM) and was found to depend on the blend ratio as well as the chemical structure of the blend components. The spin speed, which determines the thickness of the spin-coated thin films, was also found to influence the morphology. Secondary ion mass spectrometry (SIMS) was used for depth profiling of the chemical composition in thin films of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-5,5-(4´,7´-di-2-thienyl-2´,1´,3´-benzothiadiazole)] (LBPF5) blended with PCBM. The films were found to be vertically phase separated with a four-fold multilayered structure.
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Steffl, Thomas. "Rheological and film blowing properties of various low density polyethylenes and their blends." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972028625.
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Belyamani, Imane. "Développement d'un matériau thermoplastique biodégradable et hydrosoluble à base d'une protéine du lait." Phd thesis, Université Jean Monnet - Saint-Etienne, 2011. http://tel.archives-ouvertes.fr/tel-00702749.
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La biomasse représente l'une des principales alternatives à l'utilisation du pétrole dans la plasturgie. Grâce à leurs propriétés fonctionnelles, les caséinates sont une matière première prometteuse pour la fabrication de films plastiques pour des applications dans l'emballage biodégradable et hydrosoluble. La transformation du caséinate de sodium par les techniques habituellement utilisées dans la plasturgie a été démontrée. Des extrudats de caséinate plastifié au glycérol ont été obtenus au moyen d'une extrudeuse bi-vis corotative. La caractérisation physico-chimique du matériau obtenu a confirmé la thermostabilité de cette protéine et a montré la dépendance du comportement du matériau vis-à-vis de l'humidité ambiante. Pour une variation du taux d'Humidité Relative, de 40 à 90% et une augmentation de la concentration du glycérol, plastifiant hygroscopique, le matériau passe d'un état vitreux (rigide) à un état caoutchouteux (mou). Des films fins ont été ensuite réalisés, à partir des extrudats thermoplastiques, par extrusion gonflage. La perméabilité à la vapeur d'eau des films de caséinate de sodium a été étudiée et a montré que ces matériaux sont de mauvaises barrières à l'humidité. La deuxième partie a été consacré à l'étude de mélanges caséinate de sodium/caséinate de calcium d'un côté et caséinate de sodium/PBAT de l'autre. Le mélange des deux caséinates a permis d'augmenter la tenue mécanique du mélange, à partir de 50% de caséinate de calcium, et de retarder le transfert hydrique à travers le film. Dans le même sens, l'ajout du PBAT, a augmenté jusqu'à deux fois plus, le module d'Young des mélanges mais a baissé la résistance au transfert d'humidité du film à cause de l'incompatibilité des deux polymères.
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Wang, Shiping. "THICKNESS AND CRYSTALLINITY DEPENDENT SWELLING OF POLY (ETHYLENE OXIDE) /POLY (METHYL METHACRYLATE) BLEND FILMS." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1556831245474707.
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Schillebeeckx, Sep. "Morphology of Dip-Coated Polymer Blend Films in Organic Photovoltaics, a Comparison of solvents." Thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-69359.
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Liu, Xiangyu. "Highly Ordered Phase-separated PS/PMMA Blend Thin Films Structures via Capillary Force Lithography." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1462467586.
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Steffl, Thomas [Verfasser]. "Rheological and film blowing properties of various low density polyethylenes and their blends / Thomas Steffl." Aachen : Shaker, 2004. http://d-nb.info/1170529844/34.
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Paul, Rituparna. "Stability and Morphological Evolution in Polymer/Nanoparticle Bilayers and Blends Confined to Thin Film Geometries." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/28747.
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Thin film bilayers and blends composed of polymers and nanoparticles are increasingly important for technological applications that range from space survivable coatings to novel drug delivery systems. Dewetting or spontaneous hole formation in amorphous polymer films and phase separation in multicomponent polymer films can hinder the stability of these systems at elevated temperatures. Hence, fundamental understanding of dewetting and phase separation in polymer/nanoparticle bilayer and blend films is crucial for controlling transport and thermomechanical properties and surface morphologies of these systems. This dissertation provides studies on morphological evolution driven by phase separation and/or dewetting in model polymer/nanoparticle thin film bilayers and blends at elevated temperatures.
Morphological evolution in dewetting bilayers of poly(t-butyl acrylate) (PtBA) or polystyrene (PS) and a polyhedral oligomeric silsesquioxane (POSS), trisilanolphenyl-POSS (TPP) is explored at elevated temperatures. The results demonstrate unique dewetting morphologies in both PtBA/TPP and PS/TPP bilayers that are significantly different from those typically observed in dewetting polymer/polymer bilayers. Upon annealing the PtBA/TPP bilayers at 95°C, a two-step dewetting process is observed. PtBA immediately diffuses into the upper TPP layer leading to hole formation and subsequently the holes merge to form interconnected rim structures in the upper TPP layer. Dewetting of both the TPP and PtBA layers at longer annealing times leads to the evolution of scattered holes containing TPP-rich, fractal aggregates. The fractal dimensions of the TPP-rich, fractal aggregates are ~2.2 suggesting fractal pattern formation via cluster-cluster aggregation. Dewetting in PS/TPP bilayers also proceeds via a two-step process; however, the observed dewetting morphologies are dramatically different from those observed in PtBA/TPP bilayers. Cracks immediately form in the upper TPP layer during annealing of PS/TPP bilayers at 200°C. With increasing annealing times, the cracks in the TPP layer act as nucleation sites for dewetting and aggregation of the TPP layer and subsequent dewetting of the underlying PS layer. Complete dewetting of both the TPP and PS layers results in the formation of TPP encapsulated PS droplets.
Phase separation in PtBA/TPP thin film blends is investigated as functions of annealing temperature and time. The PtBA/TPP thin film blend system exhibits an upper critical solution temperature (LCST) phase diagram with a critical composition and temperature of 60 wt% PtBA and ~70°C, respectively. Spinodal decomposition (SD) is observed for 60 wt% PtBA blend films and off-critical SD is seen for 58 and 62 wt% PtBA blend films. The temporal evolution of SD in 60 wt% PtBA blend films is also explored. Power law scaling for the characteristic wavevector with time (q ~ t^n with n = -1/4 to -1/3) during the early stages of phase separation yields to domain pinning at the later stages for films annealed at 75, 85, and 95°C. In contrast, domain growth is instantly pinned for films annealed at 105°C.
Our work provides an important first step towards understanding how nanoparticles affect polymer thin film stability and this knowledge may be utilized to fabricate surfaces with tunable morphologies via controlled dewetting and/or phase separation.Ph. D.
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Okerberg, Brian. "Morphological Studies of Crystallization in Thin Films of PEO/PMMA Blends." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29213.
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Morphological development during crystallization of thin films of poly(ethylene oxide) (PEO) / poly(methyl methacrylate) (PMMA) blends has been reported. Studies have focused on the effects of the blend composition, PMMA molecular weight, film thickness, and crystallization temperature on the observed crystal morphology. As the blend composition was varied from 90 to 30 wt% PEO, the crystal morphology varied from spherulites to needles and dendrites. Variation of the crystallization temperature and PMMA molecular weight resulted in similar changes in morphology. A morphological map demonstrating the roles of the experimental controls on the observed crystal morphology has been developed. This map was used as a tool for more detailed studies of the observed morphologies and morphological transitions. The dendritic region of the map (~ 30 = 40 wt% PEO) was studied in detail. Changes in the diffusion length were achieved through variation of the PMMA molecular weight, and were shown to influence the secondary sidebranch spacing. Sidebranch spacing measurements revealed that coarsening of the dendritic microstructure occurred well after the competition between diffusion fields of neighboring dendrite arms vanished, indicating the existence of another coarsening mechanism. These studies of dendritic sidebranching indicate that polymer dendrites develop by mechanisms similar to those in small molecules and metals. A number of in-situ observations of morphological transitions have also been reported, including a dense-branched morphology (DBM)/dendrite transition, a DBM/stacked-needle/needle transition, and a transition from dendrites with 90o sidebranching to dendrites with 45o branching or a dense-branched morphology, both of which grow at 45o to the original dendrite trunk. The DBM/dendrite transition occurred over a range of crystallization temperatures, indicating that the transition is not sharp. Crystal growth rate measurements verified this result. The DBM/stacked-needle/needle transitions demonstrated distinct jumps in the crystal growth rate, indicating a change in the growth mechanism or direction. For the transition involving a change in the growth direction, the effective level of noise (fluctuation) was found to be important in morphological selection. The results of this work have helped to define new directions for the study of crystal morphologies, especially in the areas of spherulite formation and dendritic growth.Ph. D.
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Tong, Xinjie. "Production and Characterization of Crude Glycerol-Based Waterborne Polyurethanes and Their Derived Blend Films with Protein." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406041210.
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Scheurer, Amber. "Assessing the viability of sol-gel nimgo films for solar blind detection." Honors in the Major Thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/507.
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Wide bandgap semiconductors have been broadly investigated for their potential to detect and emit high energy ultraviolet (UV) photons. Advancements in deep UV optoelectronic materials would enable the efficient and affordable realization of many medical, industrial and consumer UV optical devices. The traditional growth method, vacuum deposition, is an extremely complicated and expensive process. Sol-gel processing dramatically simplifies facility requirements and can be scaled to industrial size. The work presented here involves a novel study of the ternary wide bandgap material Ni1-xMgxO. Films were developed by sol-gel spin coating for investigation of material and electrical properties. This method produced films 200-600 nm thick with surface roughness below 4 nm RMS. Sintered films indicated an improvement from 60% to 90% transmission near the band edge. Additionally, compositional analysis was performed by X-ray Photoelectron Spectroscopy and film defects were characterized by photoluminescence using a continuous wave He-Cd UV laser, revealing the expected oxygen defect at 413nm. This film growth technique has produced thin polycrystalline films with low surface roughness and a high degree of crystalline orientation; crucial characteristics for semiconductor devices. These films have demonstrated the ability to be tuned over the full compositional range from the bandgap of NiO (3.6 eV) to that of MgO (7.8 eV). Optoelectronic devices produced by standard photolithographic techniques are discussed as well as the electrical transport properties of their metal contacts. Based on initial results, these films have demonstrated strong potential as solar blind detectors of UV radiation.B.S.E.E.
Bachelors
Engineering and Computer Science
Electrical Engineering
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Lohmeier, Keri Lee. "An Analysis of Disability Specific Curriculum In A Specialized School for the Blind: A Case Study." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1315%5F1%5Fm.pdf&type=application/pdf.
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Jin, Jie. "Chitosan/PEO blend films crosslinked by genipin as potential membranes for controlled drug release and protein separation." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/7687.
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This study was conducted in order to develop novel chitosan/poly(ethylene oxide)(PEO) blend films crosslinked by genipin as potential membranes for potential medical applications, such as controlled drug carriers and separation of proteins from eleutherococcuss enticosus (ES). Genipin, a naturally occurring and non-toxic crosslinking reagent, was used to form chitosan and chitosan/PEO blend networks. Genipin is found in traditional Chinese medicine and extracted from Gardenia fruit. Importantly,it overcomes the problem of physiological toxicity inherent in the use of common synthetic chemicals as crosslinking agents. The miscibility and morphology of chitosan /PEO blends were examined by means of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and small angle X-ray scattering (SAXS). The experimental results indicate that the chitosan/PEO blends are miscible over the whole composition range. A phenomenon was observed for chitosan/LPEO (lower molecular weight PEO) blends: when the composition of chitosan was less than 60% by weight, the melting points increased as the composition of chitosan was increased. It is believed that there are strong molecular interactions between chitosan molecules and the molecules in the crystalline phase of LPEO in the chitosan ALPEO blends. FT-IR and UV spectra analysis of the crosslinking reaction of chitosan revealed that the hydroxyl groups (3400 cm-1) and the amide groups (1645 cm-) in chitosan participated actively in the reaction. SAXS results showed that a heterogeneous structure exists in the chitosan/HPEO (or /LPEO) blend networks. Crosslinking by genipin restricts crystallisation and leads to smaller crystals. The mechanical properties, the stability in water, the swelling behaviour and surface properties of the films were also investigated. (Continues...).
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Holliday, Nathan. "Processing and Properties of SBR-PU Bilayer and Blend Composite Films Reinforced with Multilayered Nano-Graphene Sheets." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1458300045.
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Jones, Gavin B. "Investigating self-assembled monolayers and understanding small molecule/polymer blend thin-films in organic field-effect transistors." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/71007/.
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Organic Thin-Film Transistors (OTFTs) are now surpassing the performance of amorphous silicon based devices which once set the benchmark. State of the art development of OTFTs in active-matrix organic light emitting diodes (OLEDs) for flexible displays has shown the potential for future applications utilising organic materials. This unprecedented advancement of flexible base electronics is now at the forefront of research and development in the electronics industry. Although charge-carrier mobility has now exceeded expectations the processing of organic materials and device functionality is still under intense investigation. Through understanding energetic interactions and charge-carrier properties at the electrode/organic semiconductor (OSC) interface alongside morphological structuring of the thin-film active layer, a more complete understanding of OTFTs can be reached. Active layers formed of a soluble small molecule blended with a polymer binder have shown significant improvements in OTFT operational performance and device yield due to enhanced morphological effects. This thesis will primarily discuss the implementation of 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) blended with poly(4-methylstyrene) (P4MS) in the expectation of enhanced device performance offering heightened charge-carrier mobility. Through investigative work conducted in this thesis into self-assembled monolayer (SAM) formation on the source/drain electrodes (Chapter 3), changes in the surface properties of the metal contact and the resulting interfacial properties at the electrode/OSC interface are correlated to OTFT performance, alongside morphological changes in the active layer and its relation to charge-carrier conduction in TIPS/P4MS thin-films (Chapter 4). Additional studies concerning 2,8-difluoro-5,11–bis (triethylsilylethynyl) anthradithiophene (diF-TES-ADT) are also discussed (Chapter 5) relating to similar processing and fabrication conditions.